Hi there and welcome
You will have to reset the iPhone, there is no other way to remove this.
To do the reset
Connect the phone to the computer and open itunes
Hold the power and volume down buttons until you see in iTunes
"iTunes has detected an iPhone in recovery mode..."
Click Restore Phone, let this complete and it should now work as it will be like new
I can also do these steps for you, and have made a request via Additional Services. This is optional, and if you choose to do this, I can, with your permission, remote into your computer while you watch and do all these steps (and deal with any problems that arise during them) for you. Or if you do not choose to take this service, we can continue here. This is no problem at all. Just let me know please.
Else let me know the results please